The Design And Experiment Of Low Damage Threshing Mechanism Of Soybean Harvester

During the soybean production process,the harvest operation is one of the key links,most areas in our country has achieved mechanized harvesting now,but the breakage problem is very serious.It is important to promote the soybean industry in China to increase the research on the damage mechanism of soybean and to design a harvester suitable for soybean harvest and reduce the damage rate of soybean.Aiming at the problem of soybean mechanized harvest damage,this paper studies the physical characteristics of soybean itself and the main causes of damage caused by soybean mechanized harvesting.Through research,we mastered the physical properties of soybean and established the threshing system simulation model,design a soybean combine harvester threshing machine that meet the quality evaluation criteria.The main contents of this paper are as follows:(1)The physical characteristics of soybean were studied.The complete plant of five soybean cultivars in Huang-Huai-Hai region was collected and the physical properties of these five varieties of soybean,pod and stalk were compared by universal testing machine.Soybean and pods were tested in three compression directions;Bending tests and shear tests were performed on the stalk.(2)After analyzing the whole process of the soybean machine,the threshing process with the greatest damage was found out,and the key components in the threshing device of the rice-wheat combine harvester were redesigned from the physical characteristics of the soybean: including the design of spiked-drum,the design of the rollers rotate plate,the design of the concave grid,the influence of the Rotating speed of the drum sprocket design.(3)The simulation model of threshing system was established by EDEM,including the modeling of soybean particles,modeling of stem,modeling of threshing mechanism,modeling of particle plant,etc.The simulation model was used to simulate the single factor and four levels,and research the effects of roller speed,pinning angle and threshing gap on fracture rate.(4)Narrow the scope of the design plan according to the result of simulation analysis,redesign,and the three factors-levels center combination field test is carried out,processing analysis of field test results,find out the optimal parameter combination,and get the influence law of the field experiment and simulation test to do comparative analysis.In this paper,the main research results are:(1)The maximum load of the three forces in the direction of the soybean and the pods,and the damage forms when they are subjected to the maximum compressive force in the three forces;the maximum bending force,shear force,elastic modulus data of the soybean stem were obtained and the regularity of their changes with the height of the stem.Test samples including five soybean varieties in the Huang-Huai-Hai region,with strong representative.Which provides a theoretical basis for the further study of the interaction between soybean,pod and stem and the components of the harvester,and provides the mechanical parameters of each material for the simulation experiment.(2)A simulation model of threshing system was established.The field test shows that the model in the analysis of drum speed and the angle of the impact of the damage rate of high reliability.There are some shortcomings in the analysis of the effect of threshing gap on the damage rate,and this defect is mainly due to the problem of soybean pod modeling.In future studies,the reliability of the modeling of soybean pods will be further improved.After the rational changes of the particle model,mechanism model and material properties in this model,it can be used to study the threshing system of wheat and rice.(3)The improved design of the soybean harvester with breakage rate to meet the operational quality evaluation criteria was completed.The field test results show that when the drum speed is 354 r/min,the spike-tooth Angle is 16 °,threshing clearance is 32 mm,the concave grid is 15 mm,the breakage rate is 4.04%,the impurity rate is 1.42%,loss rate is 1.67%.Reached the soybean combine work quality evaluation standard that the breakage is not more than 5%,the impurity rate not greater than 5%,the loss rate is not more than 3%.